package thinking.concurrency;

import java.util.ArrayList;
import java.util.List;
import java.util.Random;
import java.util.concurrent.DelayQueue;
import java.util.concurrent.Delayed;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;

import static java.util.concurrent.TimeUnit.MILLISECONDS;
import static java.util.concurrent.TimeUnit.NANOSECONDS;

/**
 * 测试了DelayQueue
 */
class DelayedTask implements Runnable, Delayed {
    private static int counter = 0;
    private final int id = counter++;
    private final int delta;
    private final long triger;
    protected static List<DelayedTask> sequence = new ArrayList<>();
    public DelayedTask(int delayMilliseconds) {
        delta = delayMilliseconds;
        triger = System.nanoTime() + NANOSECONDS.convert(delta, MILLISECONDS);
        sequence.add(this);
    }
    public long getDelay(TimeUnit unit) {
        return unit.convert(triger - System.nanoTime(), NANOSECONDS);
    }
    public int compareTo(Delayed arg) {
        DelayedTask that = (DelayedTask) arg;
        if (triger < that.triger) return -1;
        if (triger > that.triger) return 1;
        return 0;
    }
    public void run() {
        System.out.println(this + " ");
    }
    public String toString() {
        return String.format("[%1$-4d]", delta) + " Task " + id;
    }
    public String summary() {
        return "(" + id +":" + delta + ")";
    }
    public static class EndSentinel extends DelayedTask {
        private ExecutorService exec;
        public EndSentinel(int delay, ExecutorService e) {
            super(delay);
            exec = e;
        }
        public void run() {
            for (DelayedTask pt : sequence) {
                System.out.println(pt.summary() + " ");
            }
            System.out.println(this + " Calling shutdownNow()");
            exec.shutdownNow();
        }
    }
}
class DelayedTaskConsumer implements Runnable {
    private DelayQueue<DelayedTask> q;

    public DelayedTaskConsumer(DelayQueue<DelayedTask> q) {
        this.q = q;
    }
    public void run() {
        try {
            while (!Thread.interrupted())
                q.take().run();
        } catch (InterruptedException e) {

        }
        System.out.println("Finished DelayedTaskConsumer");
    }
}

public class DelayQueueDemo {
    public static void main(String[] args) {
        Random rand = new Random(47);
        ExecutorService exec = Executors.newCachedThreadPool();
        DelayQueue<DelayedTask> queue = new DelayQueue<>();
        for (int i = 0 ; i < 20; i++)
            queue.put(new DelayedTask(rand.nextInt(5000)));
        queue.add(new DelayedTask.EndSentinel(5000, exec));
        exec.execute(new DelayedTaskConsumer(queue));
    }
}
